1. Field of the Invention
The present invention relates to an image processing apparatus for mapping a position of an imaging object and also for identifying an object within a three-dimensional space from a camera image produced by imaging the imaging object by a television camera which moves while being connected to a computer.
2. Description of the Related Art
Conventionally, as the method for mapping positions of objects within camera images, the below-mentioned first, second, and third methods are known. The first and second methods are described in, for instance, the Japanese publication "PLANT OPERATION MONITORING MAN/MACHINE INTERFACE WITH USING DIRECT OPERATION TO IMAGE" (written by M. TANI et al, Institute of Electrical Society D, volume 111, No. 12, 1991, pages 1023 to 1030). The third method is disclosed in Japanese Laid-open Patent Application No.5-334438 opened in 1993 filed by the Applicant.
(1) The first method is such a mapping method that while the camera image display range is defined as the two-dimensional orthogonal coordinate space, the object position is given as the two-dimensional orthogonal coordinates. In this method, while the range represented in the camera image is defined as the two-dimensional orthogonal coordinates space, the object position is given as the coordinates within this two-dimensional orthogonal coordinate space. In other words, the projection of the three-dimensional coordinates of the object is defined by the two-dimensional coordinates within the camera image of the fixed camera. PA0 (2) The second method is such a mapping method that while the camera image is set as the projection image of the three-dimensional space to the two-dimensional space, the object position and the camera position are given as the two-dimensional orthogonal coordinates. In this mapping method, the position of the camera and the actual position of the object are given by the coordinates within the three-dimensional orthogonal coordinate space. As a consequence, even when the camera parameter is changed, the projection calculation about the three-dimensional coordinates of the object position to the two-dimensional coordinates is executed, so that the coordinates of the object position on the projection plane can be obtained. PA0 (3) The third mapping method is such a mapping method that the camera image is set as the projection image of the three-dimensional coordinate space to the two-dimensional space while setting the camera position as the origin, and the object position is given as the three-dimensional coordinates while setting the camera position as the original. In this mapping method, the object position is mapped into the three-dimensional space by way of the polar coordinates while setting the camera position as the original with employment of the coordinate of the summit of the camera image display range as the two-dimensional coordinate space, the object coordinate within the display range, and the camera parameter. Also, as the object identifying method, the cursor figure for instructing the object image within the camera image display range is set, and the position of this cursor figure is mapped by way of the above-described mapping method. Similarly, the point position instructed with the camera image display range is mapped by way of the above-described mapping method, and the position of the cursor figure is compared with the point position in the polar coordinates, so that the object related to the instructed point is identified. PA0 (1) In accordance with the first mapping method, when the camera parameters such as the position, the elevation angle, the horizontal angle, and the field angle of the camera are changed, the coordinates of the object positions within the image display range are also changed. Then, when the object position is mapped, the respective camera images having the different camera parameters must be mapped. PA0 (2) In accordance with the second mapping method, when the coordinates of the object position are set, the three-dimensional coordinate data must be entered. Also, the complex three-dimensional projection calculation must be carried out every time the camera parameter is changed. PA0 (3) The third mapping method may be readily applied to such an imaging system that the camera parameters other than the camera position are changed. Moreover, the amount of the projection calculation is small and the data setting/inputting operation can be simply executed. However, this third mapping method could not be applied to such an imaging system with employment of the moving camera, namely the camera position is changed.
However, the above-described conventional mapping methods suffers from the following problems: